I use the option under MCCC Population Control to force the game to only draw townies from my tray exactly how I created them (albeit, I've noticed occasionally, they are spawning either as occults, or in much darker skintones). If I want specific Sims to have an NPC role, I use Copy/Paste under the MCCC setting after clicking on an existing NPC to replace an existing Sim with another.
And even that doesn't help. I've ended up with the MAC cosmetics added to female Sims that, otherwise, are exactly how I created them; and that there's the whole situational outfit thing.